package com.md.lesson1;

import java.util.Scanner;

public class Circle {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		System.out.println("计算圆面积\n");
		
		double π = 3.14;
		
		System.out.print("请输入圆的半径：");
		double r = scan.nextDouble();
		
		System.out.println("圆的面积是" + (π*r*r));
				
	}

}
